This invention relates generally to the field of pumps and more particularly to a jet pump having a nozzle-venturi tube combination that can be quickly and easily changed to achieve different pumping characteristics.
In the operation of jet pumps, part of the liquid is passed through a nozzle in order to create a low pressure area on the downstream side of the nozzle which assists in drawing liquid into the suction side of the pump. By varying the nozzle-venturi combination, different pumping characteristics can be provided. For example, the flow rate can be increased with a resultant lower pressure, or the pressure can be increased with a resulting lower volume rate of flow.
In the past, pumps have been provided with a nozzle-venturi unit which can be removed and replaced with different nozzle-venturi units that have smaller or larger venturi tubes in order to achieve different flow rates and pressures. An alternative arrangement has permitted either the nozzle or venturi tube or both to be separately removed and replaced. The problem with either type of arrangement is that considerable inconvenience is encountered in effecting the replacement of one component with another. First, the component that is to be installed must be located and the old component must be removed before the new one can be installed. Aside from the problems of storing the loose components that are not in use so that they are available when needed, this procedure requires assembly and disassembly operations that involve considerable time and difficulty, especially in situations where changeover between different components takes place with some frequency.
Accordingly, it is evident that there is a need for a jet pump in which the nozzle-venturi tube combination can be quickly and easily changed. It is the principal goal of the present invention to meet that need.
In accordance with the invention, a rotatable venturi cartridge is provided in the casing of a jet pump, and the cartridge includes different venturi tubes which are arranged in a circular pattern about the axis of rotation. The cartridge can be turned to align the different venturi tubes with a nozzle mounted in the pump casing. A knob which is mounted on the exterior of the pump at a conveniently accessible location is coupled with the venturi cartridge so that the knob can be turned to change the cartridge. Indicator marks o the knob provide a clear visual indication of the operating mode of the pump at each setting of the knob (i.e., a low, medium or high flow rate or the horsepower rating at the particular knob setting).
The overall result is that the pump characteristics can be changed as desired simply by turning the adjustment knob, in contrast to the considerable inconvenience that has been encountered in the past in order to change the nozzle-venturi tube combination. The advantages of the present invention are also achieved without adding appreciably to the cost of the pump and without adding significantly to the maintenance requirements.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.